Diesel fuel composition

ABSTRACT

A diesel fuel substitute composition includes an alcohol, an acetal, and an additive comprising a component selected from the group consisting of C 3-8  dialkyl ethers, alkylated phenols, R—NO 2 , and combinations thereof. A method for forming the diesel fuel substitute is also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional application Ser.No. 61/885,320 filed Oct. 1, 2013, the disclosure of which is herebyincorporated in its entirety by reference herein.

TECHNICAL FIELD

In at least one aspect, the present invention is related to substituentcompositions for diesel fuel applications.

BACKGROUND

Low-cost conveniently synthesized fuels with diesel-like characteristicshave been long sought. However, difficulties such as low lubricity, highvolatility and low energy content have limited their adoption. Thesource for such alkanes can be natural gas, coal gas, biogas or frompartial oxidation of chemical waste such as plastics.

Oxygenate blends rich in alcohols and aldehydes are produced bywell-known methods such as the partial oxidation of alkanes. It isdesirable to form a product capable of being utilized directly in acompression ignition engine from these mixtures, rather than undertakethe more circuitous methanol olefins to gasoline and distillates (MOGD)approach for conversion of oxygenates to diesel. Moreover, the organiccontent of such a fuel product can be produced entirely from the blendwith sufficient efficiency to be sold at a cost less than that oftraditional diesel on an energy equivalent basis. Large diesel demandsand scarce fuel supplies are typical of stranded areas where associatedgas is flared so in the case of partial oxidation GTL processes thisinvention meets a critical need to minimize fuel transportation.

Although lower alcohols such as methanol and ethanol are typical ofdirect partial oxidation of alkanes, neat methanol is not a suitablefuel in compression ignition internal combustion engines as it has a lowcetane number, meaning that it is difficult to self-ignite undercompression and is therefore unsuitable for usage in a diesel engine.One solution is to react the aldehydes with the alcohols in situ to formacetals such as dimethoxy methane. Dimethoxymethane, synthesized fromformaldehyde and methanol, is generally considered too volatile for usein diesel engines although it has suitable ignition characteristics forcompression ignition engines. It also possesses unfavorable lubricitycharacteristics. A solution to this problem is to selectively formacetals by reacting alcohols with carbons greater than that of ethanolwith formaldehyde and higher aldehydes. However, there is anothersignificant problem encountered with such acetals. Although the alkoxygroups of formaldehyde dialkyl acetals, corresponding to the C_(n)alkanols from which they were derived, where n is the carbon number from2 to 4, have been shown to be very diesel like in terms of viscosity,cetane number, flash point, and lubricity, they are known to formperoxides. (Murphy, M., Safety and Industrial Issues Related to the Useof Oxygenates in Diesel Fuel. SAE technical paper 1999-01-1473, 1999).Diethoxy ethyl acetal, commonly known as acetal, is particularly proneto this problem.

Hydroperoxides tend to form at the CH bond adjacent to the oxygen of thealkoxy functionality of ethers and acetals. These ethers areparticularly dangerous on the higher substituted carbons adjacent to theether (Brown et al. Organic Chemistry 5 ed.). For example, diisopropylether, having tertiary substitution at this carbon site, has a historyof dangerous explosions whereas dimethyl ether with only primarysubstitution at this carbon is generally not known for formingperoxides. Likewise, as previously mentioned, (1,1 diethoxy ethane) isknown to possess significant risk for peroxide formation. So far thisproblem has not been addressed in regards for a purely oxygenated dieselfuel substitute.

U.S. Pat. No. 2,130,080 (the '080 patent) discloses a composition whichinhibits the formation of peroxides on dialkyl ethers following exposureto atmospheric oxygen. The disclosed additive is a carbonyl group suchas a ketone or carboxylic acid with aliphatic substituents. The specificperoxide inhibitors mentioned are acetone, methyl ethyl ketone, orsalicylic acid. The '080 patent does not disclose the application ofthese inhibitors to inhibit peroxide formation on a fuel blend.Moreover, the '080 patent fails to teach the use of such compounds toinhibit peroxides on acetals.

U.S. Pat. Pub. No. 2007/0130822 discloses a biofuel compositioncontaining dimethoxymethane, however, no claim is made of the use ofhigher acetals. Furthermore, no mention is made with regards to thetendency of some of the mentioned oxygenates to form dangerousperoxides, nor is the addition of additives with substantial antioxidantproperties disclosed. In addition, many of the oxygenate additives arenot readily synthesized from the products that result from directpartial oxidation, nor is direct partial oxidation mentioned as a sourceof such oxygenates.

U.S. Pat. No. 7,615,085 (the '085 patent) discloses a mixture of acetalsand/or carbonates and/or esters to be blended with low sulfur diesel andan antioxidant additive to inhibit peroxide formation. The oxygenatedisclosed therein is a trialkyl substituted carbon in the beta positionto a polar group such as OH, aldehyde, ketone, nitro functionality.However, the '085 patent does not disclose the use of dialkyl acetalshigher (in the sense of the number of carbons in the aldehyde or ketone)than dimethoxymethane. Furthermore, the '085 patent discloses blendingof oxygenates at a concentration of 500 to 2500 parts per million offuel (v/v). Alcohols and simple dialkyl ethers are not specified asbeing part of the oxygenated blend. Moreover, the '085 patent fails toteach that ignition enhancing ability of an additive containing nitro(R—CH₂—NO2, R being an alkyl group of tertiary substitution of 2 to 20carbons) or ketone functionality for lower alcohols. Finally, the '085patent does not teach an efficient synthesis of oxygenates or theadditive synthesized from the materials inherent with direct partialoxidation.

Lower alcohols have traditionally been rendered suitable for usage incompression ignition engines when supplemented with ignition enhancersthat raise the cetane number of such mixtures. Prior art ignitionenhancers for methanol include triethyleneglycol dinitrate, octylnitrate, cyclohexyl nitrate, 2-n-butyoxyethyl nitrate, 2-methoxyethylnitrate, and tetrahydrofuryl nitrate. The synthesis of such compoundsdoes not involve materials readily obtained through direct partialoxidation. Some prior art ignition enhancers for specifically improvingethanol blends include long chain polyethylene glycols. These compoundsare also not readily synthesized from direct partial oxidation products.Moreover, the cost of these specialized compounds has been prohibitivefor wide scale adoption of methanol as a diesel fuel in compressionignition engines. Finally, experience has shown that nitrogen emissionsare not substantially increased by the usage of such nitrated compounds.

Accordingly, there is a need for improved diesel fuels that can beeconomically synthesized and which lack the said drawbacks.

SUMMARY

The present invention solves one or more problems of the prior art byproviding in at least on embodiment a diesel fuel substitutecomposition. The composition includes an alcohol having formula (1), anacetal having formula (2) or formula (3), and an additive comprising acomponent selected from the group consisting of C₃₋₈ dialkyl ethers,alkylated phenols, R—NO₂, and combinations thereof where R is aaliphatic hydrocarbon with oxygenate functionality in an alpha or betaposition to NO₂:HOCR₁R₂R₃  (1)where:

-   R₁R₂R₃ are each independently H or a C₁₋₄ alkyl;

wherein:

-   R₄, R₅ are each independently hydrogen or C₁₋₃ alkyl;-   R₆, R₇ are each independently hydrogen, methyl, or ethyl;-   R₈ is a C₁₋₄ alkyl or another acetal linkage formed from a C₂₋₅    polyol;-   R₉, R₁₀, R₁₁ are each independently C₁₋₄ alkyl; and-   n is 0, 1 or 2;-   with the proviso that the total number of carbon atoms in R₄ plus R₅    is from 1 to 3 and that the total of n plus the number of carbon    atom in R₆ plus R₇ is from 0 to 2. Advantageously, the diesel fuel    substitute composition is a liquid at standard temperature and    pressure and has a Cetane number similar to conventional diesel, an    intermediate lower heating value (70,000-80,000 Btu/gal), and better    lubricity than dimethyl ether due to higher acetals.

In another embodiment, a method of making a diesel fuel substituentcomposition is provided. The method includes a step of providing a firstmixture of C₁₋₅ alcohols, C₁₋₅ aldehydes, C₁₋₅ ketones, and C₁₋₅ organicacids. Oxygenated compounds are separated and/or dehydrated from thefirst mixture to form a second mixture. C₁₋₅ alcohols are at leastpartially separated from the second mixture to form a third mixture. Thethird mixture includes the C₁₋₅ alcohols. C₁₋₅ aldehydes and/or C₃₋₅ketones and/or C₂₋₅ alcohols and/or C₂₋₅ polyols are synthesized from aportion of the third mixture. A fourth mixture including acetals (e.g.,having formula 2 and 3) is formed from the third mixture and the C₁₋₅aldehydes and/or C₃₋₅ ketones. In a variation, olefins can besynthesized via OTO or MTO and directly hydrated to form higheralcohols, which are then react with aldehydes and/or ketones to formacetals having formula 2 or 3. Acetals are separated from the fourthmixture. An additive is blended with the acetals. The additive includesa component selected from the group consisting of C₃₋₈ dialkyl ethers,alkylated phenols, R—NO₂, and combinations thereof where R is analiphatic hydrocarbon (e.g, C₂₋₁₀ alkyl) with oxygenate functionality inan alpha or beta position to NO₂.

In the embodiments set forth above, alcohols are blended with alkylacetals, and in particular, acetals having formula 2 and 3. The productsof direct partial oxidation of alkanes are advantageously utilized withminimal processing in an unmodified compression ignition engine. Severalsafeguards are used to inhibit peroxide formation in ether containedtherein. The first of which is the use of an inert atmosphere whichprevents lower alcohol vapors from forming a flammable mixture due totheir characteristically low flashpoint. Peroxides form in the presenceof molecular oxygen and the substantial absence thereof is an addedbenefit. The second is the use of bases to suppress the formation ofperoxides. Although the present mixture is preferably anhydrous, loweralcohols, being protic solvents, will disassociate in solution much tothe same extent as water. In this capacity, water is known to inhibitperoxides. (Murphy, M., Safety and Industrial Issues Related to the Useof Oxygenates in Diesel Fuel. SAE technical paper 1999-01-1473, 1999).Finally, the problems of both characteristically poor ignitioncharacteristics of lower alcohols in compression ignition engines andperoxide formation are solved by a single compound with dualfunctionality or multiple compounds of singular functionality.Furthermore, these compounds are also conveniently synthesized from theoxygenated blend obtained through direct partial oxidation of lightalkanes in an innovative process that minimizes costly separations ofthe individual components. Advantageously, the substitute diesel fuel ofthe present invention is stable while possessing superior volatility,ignition characteristic, cold start properties, and energy densitymaking it an excellent choice in a compression ignition engine.

In another embodiment, a system for producing a substitute diesel blendis provided. The system includes a separator for removing the C₁-C₂alcohols along with higher volatility components such as acetone andmethyl esters of acetic and formic acids as well as water and acids froma raw blend to form a concentrated blend, the raw blend includingoxygenates from partial oxidation of hydrocarbon-containing gases. Theconcentrated blend includes alcohols, ketones and/or aldehydes. Thesystem also includes a station for catalyzing the formation ofacetal-containing blends from the concentrated blend, a station forremoving water from the acetal-containing blend, a station for addingadditional alcohols to the acetal-containing blend, and a stationblending adding the ignition enhancer and peroxide inhibitor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 provides a schematic depicting a system for making a substitutediesel fuel composition; and

FIG. 2 provides a schematic of the system of FIG. 1 coupled to a systemfor producing and oxygenate blend.

DETAILED DESCRIPTION

Reference will now be made in detail to presently preferredcompositions, embodiments and methods of the present invention, whichconstitute the best modes of practicing the invention presently known tothe inventors. The Figures are not necessarily to scale. However, it isto be understood that the disclosed embodiments are merely exemplary ofthe invention that may be embodied in various and alternative forms.Therefore, specific details disclosed herein are not to be interpretedas limiting, but merely as a representative basis for any aspect of theinvention and/or as a representative basis for teaching one skilled inthe art to variously employ the present invention.

Except in the examples, or where otherwise expressly indicated, allnumerical quantities in this description indicating amounts of materialor conditions of reaction and/or use are to be understood as modified bythe word “about” in describing the broadest scope of the invention.Practice within the numerical limits stated is generally preferred.Also, unless expressly stated to the contrary: percent, “parts of,” andratio values are by weight; the description of a group or class ofmaterials as suitable or preferred for a given purpose in connectionwith the invention implies that mixtures of any two or more of themembers of the group or class are equally suitable or preferred;description of constituents in chemical terms refers to the constituentsat the time of addition to any combination specified in the description,and does not necessarily preclude chemical interactions among theconstituents of a mixture once mixed; the first definition of an acronymor other abbreviation applies to all subsequent uses herein of the sameabbreviation and applies mutatis mutandis to normal grammaticalvariations of the initially defined abbreviation; and, unless expresslystated to the contrary, measurement of a property is determined by thesame technique as previously or later referenced for the same property.

It is also to be understood that this invention is not limited to thespecific embodiments and methods described below, as specific componentsand/or conditions may, of course, vary. Furthermore, the terminologyused herein is used only for the purpose of describing particularembodiments of the present invention and is not intended to be limitingin any way.

It must also be noted that, as used in the specification and theappended claims, the singular form “a,” “an,” and “the” comprise pluralreferents unless the context clearly indicates otherwise. For example,reference to a component in the singular is intended to comprise aplurality of components.

The term “alcohol” as used herein refers to C1-5 alcohols unlessotherwise specifically indicated.

The term “aldehyde” as used herein refers to C1-5 aldehydes unlessotherwise specifically indicated.

The term “ketone” as used herein refers to C1-5 ketones unless otherwisespecifically indicated.

The term “organic acid” as used herein refers to C1-5 organic acidsunless otherwise specifically indicated.

The term “carboxylic acid” as used herein refers to C1-5 carboxylicacids unless otherwise specifically indicated.

Throughout this application where publications are referenced, thedisclosures of these publications in their entireties are herebyincorporated by reference into this application to more fully describethe state of the art to which this invention pertains.

The present invention provides an oxygenated substitute diesel blend,with enhanced safety and performance, and method for its synthesis. Thissynthesis can more efficiently be performed at smaller scales thanoxygenates to diesel such that production can occur at the same point asdemand. Direct partial oxidation of alkanes produces a raw blend ofoxygenates including alcohols, aldehydes, ketones, and acids, as well aswater. The blended mixture is subjected to separations in order toobtain a product rich in aldehydes and alcohols after which it isreacted in an acid catalyzed process to produce a blended acetalmixture. This blend is further refined or blended to a large extent andblended with lighter alcohols, ethers, and compounds possessingfunctionality for ignition enhancement and peroxide inhibition.Optionally, certain aldehydes can be reduced to diols. These productsare easily derived from reactions of said oxygenates. The obtainedproduct is inexpensively produced and can be utilized as a dieselsubstitute in a compression ignition engine.

In one embodiment, a diesel fuel substitute composition is provided. Thecomposition includes an alcohol having formula (1), an acetal havingformula (2) or formula (3), and an additive comprising a componentselected from the group consisting of C₃₋₈ dialkyl ethers, alkylatedphenols (e.g., substituted or unsubstituted C₆ phenols), R—NO₂, andcombinations thereof where R is a aliphatic hydrocarbon (e.g., C₃₋₁₂aliphatic hydrocarbon or C₄₋₁₀ aliphatic hydrocarbon) with oxygenatefunctionality (e.g., OH, ether (OR), O═, and the like) in an alpha orbeta position to NO₂:HOCR₁R₂R₃  (1)where:

-   R₁R₂R₃ are each independently H or a C₁₋₄ alkyl;

where:

-   R₄, R₅ are each independently hydrogen or C₁₋₃ alkyl;-   R₆, R₇ are each independently hydrogen, methyl, or ethyl;-   R₈ is a C₁₋₄ alkyl or another acetal linkage formed from a C₂₋₅    polyol;-   R₉, R₁₀, R₁₁ are each independently C₁₋₄ alkyl;-   n is 0, 1 or 2;-   with the proviso that the total number of carbon atoms in R₄ plus R₅    is from 0 to 3 and that the total of n plus the number of carbon    atom in R₆ plus R₇ is from 0 to 2. An example of an acetal linkage    for R₈ is:

where n′ is 2 to 5 and R₆, R₇, R₉, R₁₀, R₁₁ are as set forth above.

In a refinement, R—NO₂ is described by the following formulae:

wherein X₁ is an oxygenate functionality; and

-   R′ is a C₁₋₁₂ alkyl group.    In a refinement, the X₁ is a doubly bonded oxygen atom (O═), OH, or    OR″ where R″ is a C₁₋₆ alkyl group. It should be understood that the    carbon to which X₁ is bonded can include a hydrogen atom if X₁ is    singly bonded or no hydrogen atom if X₁ is doubly bonded.

In a further refinement a carbon in R″ as described above can be bondedwith a nitrate ester ONO₂ functionality or another ether functionalitywith the proviso that at least one nitrate ester group ONO₂ is bonded toa carbon in the polyether. In a further refinement, this further etherfunctionality includes a C₂ to C₆ alkyl group

In a refinement, the alcohol having formula (1) is present in an amountfrom 0.01 to 90 mole percent, the acetal (e.g., formula 2 and 3) ispresent in an amount from 10 to 90 mole percent, and the additive ispresent in an amount 0.01 to 10 mole percent. In another refinement, thealcohol having formula (1) is present in an amount of at least in orderof increasing preference, 0.01, 1, 2, 5, 10, 20, 25, 30, 40, 50, 60, and70 mole percent. In another refinement, the alcohol having formula (1)is present in an amount of at most in order of increasing preference,10, 20, 30, 40, 50, 60, 70, 80, and 90 mole percent. In anotherrefinement, the acetal (e.g., having formula 2 and 3) is present in anamount of at least in order of increasing preference, 25, 30, 40, 50,60, 70, and 80 mole percent. In another refinement, the acetal (e.g.,having formula 2 and 3) is present in an amount of at most in order ofincreasing preference, 10, 20, 30, 40, 50, 60, 70, 80, and 90 molepercent. In another refinement, the additive is present in an amount ofat least in order of increasing preference, 0.01, 1, 2, 3, 4, 5, 6, 7and 8 mole percent. In another refinement, the additive is present in anamount of at most in order of increasing preference, 1, 2, 3, 4, 5, 6,7, 8, 9, and 10 mole percent.

In another embodiment, a method of making a diesel fuel substituentcomposition is provided. The method includes a step of providing a firstmixture of C₁₋₅ alcohols (or C₁₋₄ alcohols), C₁₋₅ aldehydes, C₁₋₅ketones, and C₁₋₅ organic acids. Oxygenated compounds are separatedand/or dehydrated from the first mixture to form a second mixture. C₁₋₅alcohols or C₁₋₄ alcohols are at least partially separated from thesecond mixture to form a third mixture. In a refinement, the C₁₋₅aldehydes and/or C₃₋₅ ketones are synthesized by oxidation or oxidativedehydrogenation of the C₁₋₅ alcohols in the third mixture. The thirdmixture includes the C₁₋₅ alcohols. C₁₋₅ aldehydes and/or C₃₋₅ ketonesand/or C₂₋₅ alcohols and/or C₂₋₅ polyols are synthesized from a portionof the third mixture. In another refinement, a portion of alcohols andpolyols for acetal formation are synthesized from olefins derived fromoxygenate to olefin technology using oxygenates in the second and thirdmixture. In another refinement, C₂₋₅ aldehydes are synthesized from ahydroformylation reaction from the third mixture.

A fourth mixture including acetals (e.g., having formula 2 and 3) isformed from the third mixture and the C₁₋₅ aldehydes and/or C₃₋₅ketones. In a refinement, the C₁₋₅ aldehydes and/or C₃₋₅ ketones used toform the acetals are synthesized by oxidation or oxidativedehydrogenation of the C₁₋₅ alcohols in the third mixture. In avariation, the acetals are formed from a reaction of C₁₋₅ or C₁₋₄alcohols and glyoxal. In a refinement, the acetal has at least onenitrate functionality. Acetals (e.g., having formula 2 and 3) areseparated from the fourth mixture. An additive is blended with theacetals. The additive includes a component selected from the groupconsisting of C₃₋₈ dialkyl ethers, alkylated phenols (e.g., C₆₋₁₂phenols), R—NO₂, and combinations thereof where R is a aliphatichydrocarbon with oxygenate functionality in an alpha or beta position toNO₂ as set forth above. In a refinement, the additive is a compound suchthat peroxide inhibition and ignition enhancement occur on a samemolecule via an Aldol reaction of a nitro-alkane on an aldehyde. Thisnitrogenated compound can be prepared from reactions involving the thirdmixture. In some refinements, a secondary alcohol is formed by fullhydrogenation of an unsaturated ketone or aldehyde produced by an Aldolcondensation of an aldehyde and a ketone or a ketone and a ketone fromthe first mixture or the second mixture or the third mixture or fourth.In other refinement, a C₂₋₅ aldehyde is derived from an Aldolcondensation of two lower aldehydes (e.g., C₁₋₃ aldehydes from firstmixture or the second mixture or the third mixture or fourth mixture)followed by a dehydration of an Aldol product to an unsaturatedaldehyde, followed by a selective hydrogenation of a carbon-carbondouble bond. In a refinement, an acetal blend includes processed C₁₋₂alcohols and the acetals preferably having formula 2 and 3.

As set forth above, acetals having formula 2 and 3 are formed from areaction of glyoxal and C₁₋₅ or C₁₋₄ alcohols from the first or secondor third or fourth mixtures. The glyoxal can be produced from glycolaldehyde. The glycol aldehyde can be produced according via condensationof formaldehyde or through hydroformylation of formaldehyde withsynthesis gas. In a refinement, glycol aldehyde is hydrogenated to formethylene glycol and reacted with C₁-C₅ aldehydes and ketones to producedioxolane, dioxolane analogs formed by higher aldehydes and ketones, andacetals with at least 1 common C₂ linkage

Direct partial oxidation of natural gas generates a liquid oxygenateblend consisting predominately of alcohols, aldehydes and water, wheremethanol and formaldehyde are found in the greatest concentrations. Inthe same process higher alcohols and aldehydes, such as those consistingof more than 2 carbon atoms (C₂+), are also produced. Examples of theseoxygenates include but are not limited to ethanol, propanol,acetaldehyde, propionaldehyde, and acetone. Smaller concentrations oforganic acids are also produced in the direct partial oxidation process.

U.S. Pat. Nos. 7,456,327; 7,578,981; 7,642,293; 7,687,669; 7,879,296;7,910,787; 8,193,254; 8,202,916; and 8,293,186 provide systems andmethods for making the first mixture. The entire disclosures of thesepatents are hereby incorporated by reference. In a variation, the firstmixture (i.e., a blend of partially oxygenated compounds) is formed byreacting a hydrocarbon-containing gas with an oxygen-containing gas toform the second mixture. The hydrocarbon-containing gas includes one ormore components selected from the group consisting of methane, ethane,propane, butane, and pentane. In a refinement, thehydrocarbon-containing gas includes methane and ethane. In a refinement,the hydrocarbon-containing gas includes two or more components selectedfrom the group consisting of methane, ethane, propane, butane, andpentane. In a refinement, the hydrocarbon-containing gas includes threecomponents selected from the group consisting of methane, ethane,propane, butanes, and pentanes. In a refinement, thehydrocarbon-containing gas includes methane, ethane and propane, butane.In another refinement, the hydrocarbon-containing gas includes at leastfour components selected from the group consisting of methane, ethane,propane, butane, and pentane. In another refinement, thehydrocarbon-containing gas includes methane, ethane, propane, andbutane. In still another refinement, the hydrocarbon-containing gasincludes methane, ethane, propane, butane, and pentane. In a refinement,the hydrocarbon gas includes 10 to 100 mole percent methane, 0 to 30mole percent ethane, 0 to 10 mole percent propane, 0 to 5 percentbutanes (n-butane, isobutane), 0 to 2 percent pentanes (n-pentane,neopentane, isopentane). In a still another refinement, the hydrocarbongas includes 30 to 80 mole percent methane, 2 to 10 mole percent ethane,0.5 to 5 mole percent propane, 0.1 to 2 percent butanes (n-butane,isobutane), 0.02 to 1 percent pentanes (n-pentane, neopentane,isopentane). In a yet another refinement, the hydrocarbon gas includes50 to 65 mole percent methane, 3 to 6 mole percent ethane, 0.5 to 2 molepercent propane, 0.1 to 1 percent butanes (n-butane, isobutane), 0.05 to1 percent pentanes (n-pentane, neopentane, isopentane). In a variation,the blend of partially oxygenated compounds (i.e., the first mixture)formed by these methods includes acetone, methanol, ethanol,isopropanol, formic acid, formaldehyde, and water. In a refinement, theblend of partially oxygenated compounds further includesdimethoxymethane, 1,1 dimethoxyethane, methyl formate, methyl acetate.In another refinement, the blend of partially oxygenated compounds alsoincludes acetic acid or esters thereof. Typically, blend of partiallyoxygenated compounds includes 0 to 10 mole percent acetone, 10 to 60mole percent methanol, 0.5 to 20 mole percent ethanol, 0.0 to 10 molepercent isopropanol, 1 to 10 mole percent acetic acid, 0.5 to 5 molepercent formic acid, 1 to 20 mole percent formaldehyde, 0 to 3 molepercent dimethoxymethane, 0 to 3 mole percent 1,1 dimethoxyethane, 0 to3 mole percent methyl formate, 0 to 3 mole percent methyl acetate, and20 to 60 mole percent water. In a refinement, the blend of partiallyoxygenated compounds includes 1 to 10 mole percent acetone, 10 to 60mole percent methanol, 1 to 20 mole percent ethanol, 0.1 to 10 molepercent isopropanol, 1 to 10 mole percent acetic acid, 0.5 to 5 molepercent formic acid, 1 to 20 mole percent formaldehyde, 0 to 3 molepercent dimethoxymethane, 0 to 3 mole percent 1,1 dimethoxyethane, 0 to3 mole percent methyl formate, 0 to 3 mole percent methyl acetate, and20 to 60 mole percent water. In another refinement, the blend ofpartially oxygenated compounds includes 2 to 10 mole percent acetone, 25to 60 mole percent methanol, 1 to 20 mole percent ethanol, 0.1 to 10mole percent isopropanol, 1 to 10 mole percent acetic acid, 0.5 to 5mole percent formic acid, 1 to 20 mole percent formaldehyde, 0 to 3 molepercent dimethoxymethane, 0.02 to 2 mole percent 1,1 dimethoxyethane,0.02 to 2 mole percent methyl formate, 0.02 to 2 mole percent methylacetate, and 20 to 60 mole percent water. In still another refinement,the blend of partially oxygenated compounds includes 3 to 10 molepercent acetone and/or 25 to 60 mole percent methanol and/or 1 to 20mole percent ethanol and/or 0.1 to 10 mole percent isopropanol and/or 1to 10 mole percent acetic acid and/or 0.5 to 5 mole percent formic acidand/or 1 to 20 mole percent formaldehyde and/or 0.02 to 1 mole percentdimethoxymethane and/or 0.02 to 1 mole percent 1,1 dimethoxyethaneand/or 0.02 to 1 mole percent methyl formate and/or 0.02 to 1 molepercent methyl acetate and/or 20 to 60 mole percent water.

With reference to FIG. 1, a schematic of a system for producing a fuelis provided. In a variation, this system is used to produce the dieselblend set forth above. In general, the system of this embodiment takes araw liquid blend of alcohols, aldehydes, esters, and ketones andseparates out lower alcohols (C₁ and C₂), and in particular methanol.The remaining alcohols, aldehydes, and ketones are subjected toacetalization with water being removed. A substitute diesel fuel isformed from the resulting products as set forth below. System 10includes separator 12 into which raw liquid blend 14 is introduced. In arefinement, the raw blend is obtained from a partial oxidation processof hydrocarbon-containing gases (e.g., methane, propane, n-butane,isobutane, etc.) as set forth in U.S. Pat. Nos. 7,456,327; 7,578,981;7,642,293; 7,687,669; 7,879,296; 7,910,787; 8,193,254; 8,202,916; and8,293,186 the entire disclosures of which are hereby incorporated byreference. Typically, liquid blend 14 is obtained by partial oxidationof a hydrocarbon-containing gas with molecular oxygen (e.g. for air),with or without a catalyst. In a particularly useful process a catalystis not used as set forth in U.S. Pat. Nos. 7,456,327; 7,578,981;7,642,293; 7,687,669; 7,879,296; 7,910,787; 8,193,254; 8,202,916; and8,293,186. In one example, a hydrocarbon-containing gas including C₁₋₅hydrocarbons is reacted with an oxygen-containing gas (e.g., air,oxygen, etc.)

In separator 12, water and acids 16 are preferentially separated fromalcohols, aldehydes, and ketones, leaving an alcohol and aldehydeenriched blend. Typically, this enriched blend includes C₁₋₅ alcoholsand C₁₋₅ aldehydes. In a refinement, the enriched blend includes C₁₋₄alcohols and C₁₋₄ aldehydes. It is readily recognized that any number ofseparation techniques are useful for obtaining a concentrated alcoholand aldehyde blend. Examples of such techniques include, but are notlimited to, fractional condensation; distillation; azeotropicdistillation; extractive distillation; vacuum distillation; fractionaldistillation; membrane, liquid-liquid extraction; dehydration overzeolites, hydroscopic polymers, and the like; and combinations thereof.In the same or subsequent step, higher volatility alcohols in the C₁-C₂range depicted by item number 18 are separated from the blend to leavebehind concentrated mixture 20 so as to reduce the formation ofdimethoxy methane (DMM) in subsequent steps. Methanol is preferentiallysubstantially removed in this step. Typically, concentrated mixture 20includes C₂₋₅ alcohols and C₁₋₅ aldehydes. In a refinement, concentratedmixture 20 includes C₂₋₄ alcohols and C₁₋₄ aldehydes. This separation isperformed by similar methods as set forth above with the specificexamples of useful separation techniques being the same. Advantageously,the methanol is recovered for subsequent processing indicated by itemnumbers 22, 23. DMM is typically not desirable for use as a fuel whenpresent in high concentrations due to its high vapor pressure and lowerenergy density. Stream 23 may contain volatile components in addition tomethanol such as light ketones (acetone), methyl acetate, and methylformate. These components are well known to be of high octane, and maybe sold as a synthetic fuel (i.e., a high octane mixture) for sparkignition engines in addition to the diesel like stream 44.

The acids recovered in stream 16 may be transformed into ketones. C₁ toC₅ acids are known to form ketones with inorganic oxide catalysts at 300to 400° C. These ketones would have a carbon number one less than thesum of the two reacting C₁-C₅ carboxylic acids with the balance carbongoing to CO₂. In the case of formic acid reacting with formic acid,formaldehyde would result. These compounds would further react to formacetals later in the process. (Carlos, J et. al., Catalytic Productionof Liquid Transportation Fuels 2.2.2.3)

Concentrated mixture 20 desirably contains less than 1 mole percentorganic acids and less than 5 mole percent water, but is rich in higher(i.e., C₂₋₄) alcohols, aldehydes, and ketones. In a refinement,concentrated mixture 20 includes less than about 1 mole percent waterand less than 0.1 mole percent organic acids and greater than 50 molepercent of a mixture of the following: C₂-C₄ alcohols, C₁-C₄ aldehydes,and C₃-C₄ ketones. Concentrated mixture 20 is then reacted over an acidcatalyst 24. Examples of suitable acid catalysts include, but notlimited to, sulfuric acid, hydrochloric acid, sulfonic acid polymer,zirconium sulphate, and combinations thereof. In a refinement, thereaction with acid catalyst 24 is performed at a temperature from about0 to 300° C. and at pressures from 0 to 100 bar gauge such that thealcohols and polyols contained in concentrated mixtures 20 and 32 in thepresence of aldehydes therein form dialkyl acetals (e.g., having formula2 and 3). In another refinement, acetals such as methyl ethyl acetalthat have a volatility substantially greater than that of water can besynthesized and separated from water by means of reactive distillation adepicted by item number 26.

In a variation of the dialkyl acetal synthesis process set forth, it isadvantageous to increase the aldehyde fraction so as to ensure theconversion of C₂₋₅ alcohols or C₂₋₄ alcohols to acetals (e.g., formula 2and 3) and to maximize the molar acetal fraction of the mixture 20. Inthis process it is desirable to produce a sufficient quantity of C₁₋₅aldehydes or C₁₋₄ aldehydes to ensure conversion of all higher (i.e.,C₂₋₄) alcohols to acetals. Dialkoxy acetals of aldehydes with increasingcarbon number are more diesel like, having higher cetane number,lubricity and energy density. There are several methods capable ofsynthesizing these aldehydes. In one refinement, formaldehyde isproduced by an oxidation reaction or adehydrogenation/oxydehydrogenation reaction. In one variation of theoxidation process, methanol, and in particular the methanol previouslyrecovered from stream 18, is reacted with an excess of air at atemperature from about 300 to 500° C. over mixed iron/molybdenum oxidecatalyst in reactor 30. Item number 32 depicts the combining offormaldehyde produced in this manner with mixture 20 for acetalformation. In a further refinement methanol is preferably obtained froma partial oxidation process of a hydrocarbon-containing gases (e.g.,methane, propane, n-butane, isobutane, etc.) as set forth in U.S. Pat.Nos. 7,456,327; 7,578,981; 7,642,293; 7,687,669; 7,879,296; 7,910,787;8,193,254; 8,202,916; and 8,293,186 the entire disclosures of which arehereby incorporated by reference. In the dehydrogenation type processes,a molar excess of methanol is typically reacted with air at 600-650° C.over a silver catalyst. C₂-C₅ aldehydes or C₂-C₄ aldehydes mayoptionally be formed by similar reactions of the corresponding higheralcohol. For example, acetaldehyde can be formed from air and ethanolwith modified copper catalysts at 250-300° C. or from air and ethanolwith silver catalysts at 0-5 bars or pressure and at 400-600° C.

In another variation the aldehyde and ketone content of mixture 20 isincreased as follows. Aldehydes are synthesized by the hydroformylationof olefins with synthesis gas. In a refinement, olefins are created bymethanol-to-olefins (MTO) methods or oxygenates-to-olefins (OTO)methods. Traditional MTO processes typically involve an equilibriumconversion of methanol to dimethyl ether (DME) followed by a reactionover a small pore zeolite at 1-10 bar. Pure DME can also be reacted overzeolites directly to create olefins. In another variation, dehydrationof the C₂-C₄ alcohols forms olefins to be used for hydroformylation. Inparticular, an alcohol is synthesized by a hydroformylation reaction ofan olefin to an aldehyde followed by a hydrogenation of the aldehyde toa primary alcohol. This can also occur in the so calledoxygenates-to-olefins (OTO) process where oxygenates such as aldehydes,ketones, and alcohols are reacted over similar small pore zeolites atsimilar temperatures and pressures to from olefins. Hydroformylation isa reaction of synthesis gas comprising H₂ and CO with an unsaturatedhydrocarbon to create an aldehyde, usually a normal aldehyde, of anincreased carbon length of +1 as compared to the unsaturatedhydrocarbon. This homogenous reaction is typically carried out in theliquid phase with rhodium or cobalt catalysts, often with phosphineligands. (Arpe, Industrial Organic Chemistry, 5ed) The synthesis gas ispreferably obtained through reforming the reject gas of the directpartial oxidation process.

Glycol aldehyde is another aldehyde that can be added to mixture 20 tolower the volatility of the corresponding acetal. When forming acetalswith alcohols, the alcohol functionality will contribute to hydrogenbonding and thus lower the volatility. Strong base catalyzedself-condensation of formaldehyde produces glycol aldehyde. Aldolcondensations also produce aldehydes with alcohol functionality.

The homogenous liquid phase reaction of formaldehyde and CO/H₂ at 50-350bar with cobalt, rhodium, or ruthenium with phosphine ligands is knownto produce glycol aldehyde as well. In a refinement, formaldehydehydroformylation and olefin hydroformylation are carried out in the samereactor.

If aldehydes are in excess in mixture 20, these previously mentionedaldehydes with alcohol functionality produced in reactor 30 may befurther hydrogenated into polyols such as diols. These diols can then bereacted with the aldehydes and alcohols present in stream 20 to producelinked acetals. In particular, the polyols can be reacted with C₁₋₄aldehydes, C₃₋₄ ketones, and C₂₋₅ dialdehydes.

As a further processing step, glycol aldehyde may be optionally oxidizedto glyoxal. This is carried out in reaction conditions similar to thosewhich form C₁₋₅ aldehydes from alcohols. Dimethyl acetals of glyoxal aresimilar to methylal in ignition performance and resistance to peroxideformation yet have a higher vapor pressure. Furthermore, one mole ofglyoxal will react with four moles of alcohols such that less aldehydeis required in stream 32 for the same effect. Similarly, glyoxal canconsume excess volatile alcohols such as methanol present in stream 20.

If aldehydes, especially formaldehyde, are present in excess of C₂-C₅alcohols or C₂-C₄ alcohols, it may be necessary to increase said alcoholfraction. This is conveniently performed by hydrogenation of the C₂-C₅aldehydes or C₂-C₄ aldehydes such as those formed via condensation orwith synthesis gas by the methods set forth above. Specifically, theC₂₋₅ aldehydes and/or C₃₋₅ ketones for acetal production can besynthesized from alcohols and synthesis gas in a homologation reactionwhich creates aldehydes and/or alcohols. The hydrogenation may beperformed with standard hydrogenation catalysts in the liquid phase orheterogeneously at 0-200 bars. Synthesis gas may optionally be a sourceof hydrogen. As previously stated, if the aldehyde contains at least oneother aldehyde, ketone, or alcohol functionality, the derivative will bea polyol. For example, glycol aldehyde will form ethylene glycolfollowing hydrogenation. Unsaturated carbon bonds may also be optionallyhydrogenated in the same reactor.

After the majority of C₂₋₄ alcohols have been converted to dialkylacetals, the acetal-containing blend 28 is separated at separator 34from the water generated in the dialkyl acetal synthesis process anddisposed of as indicated by item number 36. The acetal rich stream 38 isthen mixed with additional alcohols 39 (preferentially methanol) notsubmitted to the acetal synthesis process via stream 32 as well asadditive compounds 40 derived from the oxygenated mixture at mixingstation 41, which increase both the ignition properties and inhibitperoxide formation. Acetals, especially those containing alkyl groupshigher than that of dimethoxymethane, and ethers containing alkyl groupshigher than that of dimethyl ether, are known to form dangerousperoxides with prolonged exposure to molecular O₂. These peroxides canconcentrate and detonate. The synthesis of such additive compounds is asfollows.

A C₂-C₅ aldehyde or a C₂-C₄ aldehyde with a carbon number greater thanor equal to that of acetaldehyde is obtained by the previously mentionedmethods for obtaining an aldehyde directly or derived from the productblend. Nitromethane can be synthesized by a reaction of nitric acid andC₃-C₄ alkanes. As these alkanes are the feed to direct partialoxidation, nitro alkanes would easily be synthesized by materials onhand. A base catalyzed addition similar to an Aldol reaction ofnitromethane and carbonyl compounds produces a nitro alcohol, with thealcohol in the beta position to the nitrate group. Being polar andprotic, this compound can act as an antioxidant for peroxides.

In a refinement, the alpha or beta hydroxy group on the nitro alkanolcan undergo an etherification or a trans-etherification with C₂ to C₆diols and/or C₂ to C₄ dialkyl ethers and/or C₁ to C₃ alkanols to producethe corresponding ether or poly ether substituent. The reactivity of themolecule can be increased by further esterifying remaining OH groups onsaid ether or poly ether substituent with nitric acid. The nitric acidester is well known in industry as a potent ignition enhancer. Ether andtransetherification reactions can proceed as follows. Solid acid andstrong acid catalysts such as those mentioned for acetalizationreactions are capable of forming ethers at temperatures from 100 to 250C and pressures from 50 to 500 psig. Transetherification reactions, suchas those which exchange alkoxy groups with an alcohol can be performedvia polymers with acid functionality or heteropoly acid catalystsaccording to U.S. Pat. Nos. 4,321,413, 4,579,980 and 6,730,815. None ofthese patents disclose reacting an organic nitro compound with alpha orbeta OH functionality. The diol can be obtained from afore mentionedsynthesis of diols from aldehydes, or from bio-derived sources. “NovelCatalysts for Glycol Manufacture” by Crabtree et. Al. details typicalsynthesis of diols from such sources.

If this compound is further oxidized to the ketone, this compound willinhibit peroxides as well. The nitrate group is well known to act as anignition enhancer. Therefore, the addition of this compound will providedual functionality for both peroxide inhibition and ignitionenhancement. Alternatively, the said nitro alcohol compound can bereacted with an alcohol and an aldehyde to form the acetal with nitratefunctionality. Alternatively, the nitro alcohol can be dehydrated to anitro-alkene. Addition of an alcohol over this unsaturated bond willform the corresponding nitro-ether with excellent ignition enhancingproperties.

Industrially, there are several methods used to oxidize secondaryalcohols into ketones which could be employed to oxidize the secondaryalcohol in the beta position to the NO2 group. Dehydrogenation of2-butanol is known to occur in the liquid phase with Raney nickel orcopper chromite and in the gas phase at 400-500° C. over a zinc oxide orcopper-zinc catalyst. (Arpe, Industrial Organic Chemistry, 5ed)

In another refinement, acetone is formed by oxidative dehydrogenation of2-propanol to acetone over silver or copper catalysts at 400-600° C.This reaction is analogous to the oxydehydrogenation of methanol orethanol to aldehydes described above. (Arpe, Industrial OrganicChemistry, 5ed)

Another possibility is transferring the hydrogen in the nitro alcohol toan aldehyde akin to the production of allyl alcohol from acrolein bytransferring hydrogen from 2-propanol or 2-butanol to the acroleinforming acetone or methyl ethyl ketone. This reaction is carried outover magnesium/zinc oxide catalysts at 400° C. Finally, the OH group onthe nitro alcohol might be dehydrated to form an unsaturated nitrocompound. In a reaction akin to the conversion of ethylene toacetaldehyde, an unsaturated carbon-carbon bond is oxidized to a from acarboxyl (CO) group over one of the carbons. With ethylene toacetaldehyde, this reaction is carried out in air at 110-120° C. and10-20 bar pressure. This occurs in the liquid phase of a Cu/PdCl₂ systemsimilar to the Wacker-Hoechst oxidation of ethylene to acetaldehyde.Again, it is feasible to oxidize both ethylene to acetaldehyde forhigher acetal production and the nitroalkene to the nitroketone in thesame reactor. (Arpe, Industrial Organic Chemistry, 5ed) The ketone inthe alpha position is a byproduct of this reaction. Alternatively,electrochemical methods are known to oxidize secondary alcohols toketones. Finally, traditional reagents such as hexavalent chromiumoxides may also be employed for this purpose.

Higher dialkyl ethers such as methyl ethyl ether and diethyl ether mayoptionally be added to this blend as ignition enhancers and cold startimprovers. In a refinement, these dialkyl ethers are formed by reactionof the alcohols (e.g., methanol and ethanol) formed above. Alcohols donot have favorable cold start characteristics which may be overcome bythe addition of these ethers. Cetane improvement would also result fromthe usage of dialkyl ethers. Convenient ether forming reactions includeacid catalyzed ether synthesis from alcohols as well as methanoladdition over an unsaturated carbon-carbon bond. The alcohols would beproduced in the afore mentioned methods.

The final product blend 44 therefore presents a higher cetane number andlubricity than C₁ alcohols and acetals, and is not hampered by the poorignition characteristics of lower alcohols alone (C₁ and C₂) or the highvolatility of dimethoxymethane. In a refinement, formation of peroxidesis limited by the addition of an inhibitor compound which also functionsas an ignition enhancer. Moreover, the poor cold start characteristicsof methanol are mitigated. Finally, chemicals produced in this mannersuch as polyols and aldehydes may be utilized for their value aschemicals aside from their energy value as a substitute diesel fuel.

With reference to FIG. 2, a schematic illustration depicting thecoupling of the substitute diesel fuel system of FIG. 1 coupledcarbonaceous gas to oxidized products in a gas-to-chemicals (GTL)process of U.S. Pat. No. 9,255,051 is provided. The entire disclosure ofU.S. Pat. No. 9,255,051 is hereby incorporated by reference in itsentirety. In a refinement, the system of FIG. 1 is coupled to thegas-to-chemicals system in a continuous fashion. Homogeneous directpartial oxidation is performed in a reactor 50 which is supplied with ahydrocarbon-containing gas 52 and an oxygen-containing gas 54. In arefinement, the reaction is operated at pressures from about 450 to 1250psia and temperatures from about 350 to 450° C. In particular,hydrocarbon-containing gas 52 and an oxygen-containing gas 54 react in avessel to form a first product blend which is a blend (i.e., a mixture)of partially oxygenated compounds that include formaldehyde. In arefinement, the first product blend and/or output stream 14 includeC₁₋₁₀ alcohols and/or C₁₋₅ aldehydes and/or C₃-C₅ ketones. In anotherrefinement, the first product blend and/or output streams 31, 32 includean alcohol selected from the group consisting of methanol, ethanol,propanols, butanols, pentanols and combinations thereof, and/oraldehydes selected from the group consisting formaldehyde, acetaldehyde,propionaldehyde and/or ketones selected from the group consisting ofacetone, methyl ethyl ketone, pentanones, and combinations thereof. Inanother refinement, the first product blend and/or output streams 31, 32include an alcohol selected from the group consisting of methanol,ethanol, and combinations thereof, and aldehyde selected from the groupconsisting formaldehyde, acetaldehyde, and combinations thereof.Examples of systems and methods of performing the partial oxidation asset forth in U.S. Pat. Nos. 8,293,186; 8,202,916; 8,193,254; 7,910,787;7,687,669; 7,642,293; 7,879,296; 7,456,327; and 7,578,981; the entiredisclosures of which are hereby incorporated by reference. In arefinement, the hydrocarbon-containing gas includes C₁₋₁₀ alkanes orC₁₋₅ alkanes. In another refinement, the hydrocarbon-containing gasincludes an alkane selected from the group consisting of methane,ethane, propanes, butanes, pentanes and combinations thereof. In anotherrefinement, the hydrocarbon-containing gas includes an alkane selectedfrom the group consisting of methane, ethane, and combinations thereof.In another refinement, the hydrocarbon-containing gas includes acomponent selected from the group consisting of H₂, CO₂, CO, N₂, H₂S,H₂O, oxygenates, and combinations thereof.

Examples of oxygen containing gas include molecular oxygen which may bein the form of concentrated oxygen or air. In a refinement, theoxygen-containing gas stream is made oxygen rich (e.g., by passing airthrough a membrane to increase oxygen content). The low conversion andselectivity of homogeneous direct partial oxidation requires that arecycle loop is utilized to increase the overall carbon efficiency.

Following partial oxidation reaction the reactant stream is rapidlycooled in a series of heat exchangers 60 and 62 to prevent decompositionof the produced oxygenates. The heat energy transferred by exchanger 62might optionally be used to provide energy which may be used in thecreation of synthesis gas. After cooling the liquids are separated fromthe gas stream as station 64. The gas stream is then submitted to aseparation process for removal of non-hydrocarbon fractions at station66 which may be performed via scrubbing, membrane separation, adsorptionprocesses, cryogenic separations, or by purging a small gas fraction. Ifstation 66 is a liquid scrubbing system, liquid products are sent to aflash drum 70 where dissolved gases are removed. Non-hydrocarbon gases74 are removed from the recycle loop, and the hydrocarbon gases 76 arethen recycled to combine with fresh methane gas 80 which has beenpressurized to the pressure of the loop by compressor 82. The streamcomposed of recycled hydrocarbons plus fresh methane gas is pressurizedto make up for pressure losses in the recycle loop, preheated via thecross exchanger 60 and further by the preheater 86, when necessary, tomeet the desired reaction conditions.

Liquids generated by the gas-to-chemicals process are composedpredominantly of alcohols and aldehydes (e.g., methanol, ethanol andformaldehyde) as set forth above. The raw liquid stream 92 generated bythe GTL process is generally composed of 50-70% alcohols and 5-20%aldehydes 15-30% water. Downstream processing of these liquids mayinclude a number of different synthesis routes to higher-value chemicalsand fuels, but simple distillation of alcohols from aldehydes isperformed in a simple fractional distillation column in which alcoholsare recovered in the distillate and the aqueous aldehyde solution fromthe column bottoms

The compositions of the gas streams obtained from separation ofnon-hydrocarbon gases 74 from the recycle loop and from degassing theliquid mixture 94 may vary significantly depending on the separationmethods employed in station 66. Stream 94 would be typically be neededto regenerate a scrubbing fluid by liberating dissolved gasses such ascarbon dioxide or carbon monoxide, which would be enriched in thisstream. Stream 94 is composed predominantly of lighter hydrocarbons andcarbon oxides (e.g., CO₂) which are soluble in the liquid solution, butare vaporized when decreasing the pressure. The stream ofnon-hydrocarbon gases 74 and stream 94 are blended to form stream 96,which is rich in synthesis gas.

While exemplary embodiments are described above, it is not intended thatthese embodiments describe all possible forms of the invention. Rather,the words used in the specification are words of description rather thanlimitation, and it is understood that various changes may be madewithout departing from the spirit and scope of the invention.Additionally, the features of various implementing embodiments may becombined to form further embodiments of the invention.

What is claimed is:
 1. A composition comprising: an alcohol havingformula (1):HOCR₁R₂R₃  (1) where: R₁R₂R₃ are each independently H or a C₁₋₄ alkyl;an acetal having formula (2) or formula (3):

where: R₄, R₅ are each independently hydrogen or C₁₋₃ alkyl; R₆, R₇ areeach independently hydrogen, methyl, or ethyl; R₈ is a C₁₋₄ alkyl oranother acetal linkage formed from a C₂₋₅ polyol; R₉, R₁₀, R₁₁ are eachindependently C₁₋₄ alkyl; n is 0, 1 or 2; with the proviso that thetotal number of carbon atoms in R₄ plus R₅ is from 0 to 3 and that thetotal of n plus the number of carbon atom in R₆ plus R₇ is from 0 to 2;and an additive comprising a component selected from the groupconsisting of C₃₋₈ dialkyl ethers, alkylated phenols, R—NO₂, andcombinations thereof where R is a aliphatic hydrocarbon with oxygenatefunctionality in an alpha or beta position to NO₂.
 2. The composition ofclaim 1 wherein the additive is an ignition enhancer.
 3. The compositionof claim 1 wherein the additive is a peroxide inhibitor.
 4. Thecomposition of claim 1 wherein: the alcohol having formula (1) ispresent in an amount from 0.01 to 90 mole percent: the acetal is presentin an amount from 10 to 90 mole percent; and the additive is present inan amount from 0.01 to 10 mole percent.
 5. The composition of claim 1wherein the acetal is formed by reacting a polyol with the componentselected from the group consisting of C₁₋₄ aldehydes, C₃₋₄ ketones, andC₂₋₅ dialdehydes.
 6. The composition of claim 1 further comprisingmethanol.
 7. The composition of claim 1 wherein the oxygenatefunctionality is OH or O═ (carbonyl) or OR (ether).